Methods and systems for laser scan location verification and laser surgical systems with laser scan location verification

ABSTRACT

A method of verifying a laser scan at a predetermined location within an object includes imaging at least a portion of the object, the resulting image comprising the predetermined location; identifying the predetermined location in the image, thereby establishing an expected scan location of the laser scan in the image; performing a laser scan on the object by scanning a focal point of the laser beam in a scanned area; detecting a luminescence from the scanned area and identifying an actual scanned location within the image based on the detected luminescence; and determining whether the difference between the actual scanned location and the expected scan location is within a threshold value.

RELATED APPLICATIONS

This application claims priority to and is a divisional application ofU.S. Non-Provisional application Ser. No. 14/969,363, filed Dec. 15,2015, which claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Application Ser. No. 62/190,227, filed Jul. 8, 2015, all ofwhich are incorporated herein in their entirety by reference.

BACKGROUND

Cataract extraction is a frequently performed surgical procedure. Acataract is formed by opacification of the crystalline lens of the eye.The cataract scatters light passing through the lens and may perceptiblydegrade vision. A cataract can vary in degree from slight to completeopacity. Early in the development of an age-related cataract the powerof the lens may increase, causing near-sightedness (myopia). Gradualyellowing and opacification of the lens may reduce the perception ofblue colors as those shorter wavelengths are more strongly absorbed andscattered within the cataractous crystalline lens. Cataract formationmay often progress slowly resulting in progressive vision loss.

A cataract treatment may involve replacing the opaque crystalline lenswith an artificial intraocular lens (IOL), and an estimated 19 millioncataract surgeries per year are performed worldwide. Cataract surgerycan be performed using a technique termed phacoemulsification in whichan ultrasonic tip with associated irrigation and aspiration ports isused to sculpt the relatively hard nucleus of the lens to facilitateremoval through an opening made in the anterior lens capsule. Thenucleus of the lens is contained within an outer membrane of the lensthat is referred to as the lens capsule. Access to the lens nucleus canbe provided by performing an anterior capsulotomy in which a small roundhole can be formed in the anterior side of the lens capsule. A primaryincision and a sideport incision may be placed in the cornea to allowaccess for the ultrasonic tip or other instruments and to permit removalof the lens pieces. An arcuate incision may also be placed in the corneaduring cataract surgery to alter the refractive properties of thecornea. After removal of the lens nucleus, a synthetic foldableintraocular lens (TOL) can be inserted into the remaining lens capsuleof the eye.

Accurate placement of a capsulotomy incision, a primary incision, asideport incision and an arcuate incision can be important for achievinga successful outcome of cataract surgery. In automated laser surgicalprocedures, physicians generally provide the necessary parameters foridentifying the number, placement and size of incisions based onpre-treatment measurements. However, errors in data entry or lack ofproper calibration of the laser surgical system can potentially lead tothe placement of incisions at locations other than at the locationsprescribed by the user. Moreover, some laser surgery systems have notallowed real time confirmation of the location of the incision at thepredetermined location or have not provided warnings to the user if theactual placement of incisions during an automated scan is different fromthe intended location of the incisions.

Thus, methods and systems that introduce additional safeguards, such asverifying the location of a laser scan or ocular incision, would behelpful for treating patients with laser surgical systems.

SUMMARY OF THE INVENTION

Hence, to obviate one or more problems due to limitations anddisadvantages of the related art, this disclosure provides embodiments,including a method of verifying the placement of a laser scan at apredetermined location within an object comprises imaging at least aportion of the object, the resulting image comprising the predeterminedlocation; identifying the predetermined location in the image, therebyestablishing an expected scan location of the laser scan in the image;performing the laser scan on the object by scanning a focal point of alaser beam in a scanned area; detecting a luminescence from the scannedarea and identifying an actual scanned location within the image basedon the detected luminescence; and verifying whether the laser scan wasat the predetermined location based on a difference between the actualscanned location and expected scan location. Preferably, the laser beamis a pulsed laser beam having a wavelength of 320 nm to 370 nm. Theluminescence preferably has a wavelength of 400 nm or more. The step ofverifying the laser scan is at the predetermined location comprisesdetermining whether a distance between the actual scanned location andthe expected scan location is within a predetermined threshold.

In many embodiments, the object is a human eye. In other embodiments,the object is a calibration apparatus.

In many embodiments, the image comprises an array of pixels. Theexpected scan location preferably comprises one or more pixels selectedfrom amongst the array of pixels. Also, the actual scanned locationpreferably comprises one or more pixels selected from the array ofpixels. Preferably, verifying the laser scan at the predeterminedlocation comprises determining whether a distance between the actualscanned location and the expected scan location is within apredetermined threshold.

In many embodiments, the method further comprises periodicallyre-imaging the object, thereby obtaining one or more successive imagesof the object, and identifying an actual scanned location by comparing adetected luminescence of a same pixel in the array between two of thesuccessive images. Preferably, the methods include identifying adirection of the scan by comparing an actual scanned location in betweentwo or more of the successive images. A method of verifying theplacement of an ocular incision by a laser surgical system at apredetermined location within an eye comprises imaging at least aportion of the eye, the resulting image comprising the predeterminedlocation for a laser scan corresponding to the ocular incision;identifying the predetermined location in the image, therebyestablishing an expected scan location of the ocular incision in theimage; performing a laser scan on the object by scanning a focal pointof the laser beam in a scanned area, the laser scan being configured ina scan pattern for performing the ocular incision; detecting aluminescence from the scanned area and identifying an actual scannedlocation within the image based on the detected luminescence; andverifying the placement of an ocular incision based on the differencebetween the actual scanned location and expected scan location. Theluminescence preferably has a wavelength of 400 nm or more. The step ofverifying the laser scan is at the predetermined location comprisesdetermining whether a distance between the actual scanned location andthe expected scan location is within a predetermined threshold.

In many embodiments, the image comprises an array of pixels. Theexpected scan location preferably comprises one or more pixels selectedfrom amongst the array of pixels. Also, the actual scanned locationpreferably comprises one or more pixels selected from the array ofpixels. Preferably, verifying the laser scan at the predeterminedlocation comprises determining whether a distance between the actualscanned location and the expected scan location is within apredetermined threshold.

In many embodiments, the method further comprises periodicallyre-imaging the object, thereby obtaining one or more successive imagesof the eye, and identifying an actual scanned location by comparing adetected luminescence of a same pixel in the array between two of thesuccessive images. Preferably, the methods include identifying adirection of the scan by comparing an actual scanned location in betweentwo or more of the successive images.

In many embodiments, a method of verifying the calibration of a lasereye surgical system comprises imaging at least a portion of acalibration apparatus having at least one emissive surface, theresulting image comprising a predetermined location for a laser scan;identifying the predetermined location in the image, therebyestablishing an expected scan location of the laser scan in the image;performing the laser scan of the calibration apparatus by scanning afocal point of the laser beam in a scanned area; detecting aluminescence from the scanned area and identifying an actual scannedlocation within the image based on the detected luminescence; anddetermining whether the laser surgical system is calibrated based on adifference between the actual scanned location and expected scanlocation. The laser beam preferably has a wavelength of 320 nm to 370nm. The luminescence preferably has a wavelength of 400 nm or more. Thestep of verifying the laser scan is at the predetermined locationpreferably comprises determining whether a distance between the actualscanned location and the expected scan location is within apredetermined threshold.

In many embodiments, the image comprises an array of pixels. Theexpected scan location preferably comprises one or more pixels selectedfrom amongst the array of pixels. Also, the actual scanned locationpreferably comprises one or more pixels selected from the array ofpixels. Preferably, verifying the laser scan at the predeterminedlocation comprises determining whether a distance between the actualscanned location and the expected scan location is within apredetermined threshold.

In many embodiments, the method further comprises periodicallyre-imaging the object, thereby obtaining one or more successive imagesof the calibration apparatus, and identifying an actual scanned locationby comparing a detected luminescence of a same pixel in the arraybetween two of the successive images. Preferably, the methods includeidentifying a direction of the scan by comparing an actual scannedlocation in between two or more of the successive images.

In many embodiments, a laser eye surgical system, comprises a lasersource for generating a pulsed laser beam; an imaging system comprisinga detector; shared optics configured for directing the pulsed laser beamto an object to be sampled and confocally deflecting back-reflectedlight from the object to the detector; and a controller operativelycoupled to the laser source, the imaging system and the shared optics.The controller configured to: receive one or more parameters definingone or more ocular incisions; image the eye with the imaging apparatusand identify an expected scan location within the image corresponding tothe one or more ocular incisions based on the one or more parameters;scan the focal point of a laser beam; detect luminescence from theregion scanned; identify the actual scanned location within the imagebased on the detected luminescence; and provide a warning to the user ifa difference between the actual scanned location and the expected is notwithin a predetermined threshold value.

The controller may be configured to verify the laser scan is at thepredetermined location when a distance between the actual scannedlocation and the expected scan location is within a predeterminedthreshold.

The laser beam preferably has a wavelength of 320 nm to 370 nm, and theluminescence has a wavelength of 400 nm or more.

In may embodiments, the image preferably comprises an array of pixels.The expected scan location preferably comprises one or more pixelsselected from amongst the array of pixels, and the actual scannedlocation comprises one or more pixels selected from the array of pixels.

The controller is preferably configured to periodically re-image theeye, thereby obtaining one or more successive images and identifying anactual scanned location by comparing a detected luminescence of a samepixel in the array between two of the successive images. The controlleris also preferably configured to identify direction of the scan bycomparing an actual scanned location in between two or more of thesuccessive images.

This summary and the following detailed description are merelyexemplary, illustrative, and explanatory, and are not intended to limit,but to provide further explanation of the invention as claimed.Additional features and advantages of the invention will be set forth inthe descriptions that follow, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription, claims and the appended drawings.

BRIEF DESCRIPTION OF THE FIGURES

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages will be facilitated by referring to the following detaileddescription that sets forth illustrative embodiments using principles ofthe invention, as well as to the accompanying drawings, in which likenumerals refer to like parts throughout the different views. Like parts,however, do not always have like reference numerals. Further, thedrawings are not drawn to scale, and emphasis has instead been placed onillustrating the principles of the invention. All illustrations areintended to convey concepts, where relative sizes, shapes, and otherdetailed attributes may be illustrated schematically rather thandepicted literally or precisely.

FIG. 1 is a schematic diagram of a laser surgery system according tomany embodiments in which a patient interface device is coupled to alaser assembly and a detection assembly by way of a scanning assemblyand shared optics that supports the scanning assembly.

FIG. 2 is a schematic diagram of an embodiment of the laser surgerysystem of FIG. 1.

FIG. 3 is a schematic diagram of an embodiment of the laser surgerysystem of FIG. 1.

FIG. 4 is a block diagram illustrating several acts of the methods andacts for laser scan verification in many embodiments.

FIG. 5 illustrates an en face image of an eye.

FIGS. 6A and 6B illustrate a calibration apparatus.

FIG. 7A is a plan view illustrating a calibration plate according tomany embodiments that can be used to calibrate the laser surgery systemof FIG. 1.

FIG. 7B is a schematic diagram illustrating using the calibration plateof FIG. 10A to calibrate a camera of the laser surgery system of FIG. 1.

FIG. 7C is a schematic diagram illustrating using the calibration plateof FIG. 10A to calibrate the scanning assembly of the laser surgerysystem of FIG. 1.

FIG. 8 shows a plan view of a capsulotomy incision locator and across-sectional view showing projection of the capsulotomy incisionlocator on the lens anterior capsule according to many embodiments.

FIGS. 9A, 9B and 9C illustrate aspects of arcuate incisions of a corneathat can be formed by the laser surgery system of FIG. 1 according tomany embodiments.

FIGS. 10A, 10B, 10C, 10D, 10E and 10F illustrate aspects of primarycataract surgery access incisions of a cornea that can be formed by thelaser surgery system of FIG. 1 according to many embodiments.

FIGS. 11A, 11B, 11C, 11D and 11E illustrate aspects of sideport cataractsurgery access incisions of a cornea that can be formed by the lasersurgery system of FIG. 1 according to many embodiments.

FIG. 12 is a schematic diagram illustrating the use of emission from eyetissue to verify the location scan with a camera of the laser surgerysystem of FIG. 1.

FIG. 13 is a schematic diagram illustrating the en face image of the eyeprojected onto a monitor using a laser surgery system such as describedin FIG. 1.

FIG. 14 is a schematic diagram of aspects of a section scan and analong-the-cut scan for imaging areas of a cornea.

DETAILED DESCRIPTION

In the following description, various embodiments of the presentinvention will be described. For purposes of explanation, specificconfigurations and details are set forth in order to provide a thoroughunderstanding of the embodiments. It will also, however, be apparent toone skilled in the art that the present invention can be practicedwithout the specific details. Furthermore, well-known features may beomitted or simplified in order not to obscure the embodiment beingdescribed.

Systems for imaging and/or treating an eye of a patient are provided. Inmany embodiments, a shared optics provides a variable optical path bywhich a portion of an electromagnetic beam reflected from a focal pointdisposed within the eye is directed to a path length insensitive imagingassembly, such as a confocal detection assembly. In many embodiments,the shared optics is configured to accommodate movement of the patientwhile maintaining alignment between an electromagnetic radiation beamand the patient. The electromagnetic radiation beam can be configuredfor imaging the eye, can be configured for treating the eye, and can beconfigured for imaging and treating the eye.

Referring now to the drawings in which like numbers reference similarelements FIG. 1 schematically illustrates a laser surgery system 10,according to many embodiments. The laser surgery system 10 includes alaser assembly 12, a confocal detection assembly 14, a shared optics 16,a scanning assembly 18, an objective lens assembly 20, and a patientinterface device 22. The patient interface device 22 is configured tointerface with a patient 24. The patient interface device 22 issupported by the objective lens assembly 20. The objective lens assembly20 is supported by the scanning assembly 18. The scanning assembly 18 issupported by the shared optics 16. The shared optics 16 has a portionhaving a fixed position and orientation relative to the laser assembly12 and the confocal detection assembly 14. In many embodiments, thepatient interface device 22 is configured to interface with an eye ofthe patient 24. For example, the patient interface device 22 can beconfigured to be vacuum coupled to an eye of the patient 24 such asdescribed in co-pending U.S. Provisional patent application Ser. No.14/068,994, entitled “Liquid Optical Interface for Laser Eye SurgerySystem,” filed Oct. 31, 2013. The laser surgery system 10 can furtheroptionally include a base assembly 26 that can be fixed in place orrepositionable. For example, the base assembly 26 can be supported by asupport linkage that is configured to allow selective repositioning ofthe base assembly 26 relative to a patient and secure the base assembly26 in a selected fixed position relative to the patient. Such a supportlinkage can be supported in any suitable manner such as, for example, bya fixed support base or by a movable cart that can be repositioned to asuitable location adjacent to a patient. In many embodiments, thesupport linkage includes setup joints with each setup joint beingconfigured to permit selective articulation of the setup joint and canbe selectively locked to prevent inadvertent articulation of the setupjoint, thereby securing the base assembly 26 in a selected fixedposition relative to the patient when the setup joints are locked. Inmany embodiments, the laser assembly 12 is configured to emit anelectromagnetic radiation beam 28. The beam 28 can include a series oflaser pulses of any suitable energy level, duration, and repetitionrate.

In one embodiment, the laser assembly 12 incorporates femtosecond (FS)laser technology. By using femtosecond laser technology, a shortduration (e.g., approximately 10-13 seconds in duration) laser pulse(with energy level in the micro joule range) can be delivered to atightly focused point to disrupt tissue, thereby substantially loweringthe energy level required to image and/or modify an intraocular targetas compared to laser pulses having longer durations. In otherembodiments, the pulse duration of the laser pulses is generally between1 ps and 100 ns. The laser assembly 12 can produce laser pulses having awavelength suitable to treat and/or image tissue. For example, the laserassembly 12 can be configured to emit an electromagnetic radiation beam28 such as that emitted by any of the laser surgery systems described inco-pending U.S. application Ser. No. 14/069,042, entitled “Laser EyeSurgery System,” filed Oct. 31, 2013; U.S. patent application Ser. No.12/987,069, entitled “Method and System For Modifying Eye Tissue andIntraocular Lenses,” filed Jan. 7, 2011; U.S. application Ser. No.14/576,593, entitled “Confocal Laser Eye Surgery System,” filed Dec. 19,2014; and U.S. application Ser. No. 14/666,743, entitled “AutomatedCalibration of Laser System and Tomography System with FluorescentImaging of Scan Pattern,” filed Mar. 24, 2015. For example, the laserassembly 12 can produce laser pulses having a wavelength from 1020 nm to1050 nm. For example, the laser assembly 12 can have a diode-pumpedsolid-state configuration with a 1030 (+/5) nm center wavelength. Asanother example, the laser assembly 12 can produce ultraviolet lightpulses having a wavelength of between 320 nm and 430 nm, preferablybetween 320 and 400 nm, preferably between 320 to 370 nm, and morepreferably between 340 nm and 360 nm. In many embodiments, the laserpulses have a wavelength of 355 nm. The 320 nm to 430 nm light sourcemay be, for instance, a Nd:YAG laser source operating at the 3rdharmonic wavelength, 355 nm.

When an ultraviolet wavelength is used, the pulse energy of the laserpulses is generally between 0.010 and 5000. In many embodiments, thepulse energy will be between 0.1 μJ and 100 μJ, or more precisely,between 0.1 μJ and 40 μJ, or between 0.1 μJ and 10 μJ. When anultraviolet wavelength is used, a pulse repetition rate of the laserpulses is generally between 500 Hz and 500 kHz. In many embodiments, thepulse repetition rate is between 1 kHz to 200 kHz, or between 1 KHz to100 KHz.

When an ultraviolet wavelength is used, spot sizes of the laser pulsesare generally smaller than 10 μm. In many embodiments, the spot size ispreferably smaller than 5 μm, typically 0.5 μm to 3 μm.

When an ultraviolet wavelength is used, the pulse duration of the laserpulses is generally between 1 ps and 100 ns. In many embodiments, thepulse duration is between 100 ps to 10 ns, or between 100 ps and 1 ns.In a preferred embodiment, the pulse duration is between 300 ps and 700ps, preferably 400 ps to 700 ps.

In some embodiments when an ultraviolet wavelength is used, the beamquality, also referred to as M2 factor, is between 1 and 1.3. The M2factor is a common measure of the beam quality of a laser beam. Inbrief, the M2 factor is defined as the ratio of a beam's actualdivergence to the divergence of an ideal, diffraction limited, GaussianTEM00 beam having the same waist size and location as is described inISO Standard 11146.

In some embodiments when an ultraviolet wavelength is used, a peak powerdensity, obtained by dividing the peak power of the laser pulse by thefocal spot size, is generally expressed in units of GW/cm2. In general,the peak power density of the laser pulses should be sufficiently highto modify the ocular tissue to be treated. As would be understood bythose ordinarily skilled, the peak power density depends upon a numberof factors, including the wavelength of the selected laser pulses. Insome embodiments, a peak power density is generally in the range of 100GW/cm2 to 800 GW/cm2 will be used to cut ocular tissue with 355 nmlight. In some embodiments when an ultraviolet wavelength is used, thescan range of the laser surgical system is preferably in the range of 6mm to 10 mm. In some embodiments when an ultraviolet wavelength is used,spot spacing between adjacent laser pulses is typically in the range ofabout 0.20 μm to 10 μm, preferably 0.2 μm to 6 μm.

In some embodiments when an ultraviolet wavelength is used, a numericalaperture should be selected that preferably provides for the focal spotof the laser beam to be scanned over a scan range of 6 mm to 10 mm in adirection lateral to a Z-axis that is aligned with the laser beam. TheNA of the system should be less than 0.6, preferably less than 0.5 andmore preferably in a range of 0.05 to 0.4, typically between 0.1 and0.3. In some specific embodiments, the NA is 0.15. For each selected NA,there are suitable ranges of pulse energy and beam quality (measured asan M2 value) necessary to achieve a peak power density in the rangerequired to cut the ocular tissue. Further considerations when choosingthe NA include available laser power and pulse rate, and the time neededto make a cut. Further, in selection of an appropriate NA, it ispreferable to ensure that there is a safe incidental exposure of theiris, and other ocular tissues that are not targeted for cuts.

When UV wavelengths are used, the tissue modification is carried outusing chromophore absorption without plasma formation and/or withoutbubble formation and an associated cavitation event. Here, chromophoreabsorption refers to the absorption of at least a portion of theultraviolet light by one or more chemical species in the target area.The use of ultraviolet light significantly reduces the threshold forplasma formation and associated formation of cavitation bubbles but alsodecreases the threshold energy required for linear absorption enhancedphotodecomposition without the formation of cavitation bubbles for a fewreasons. First, the focused spot diameter scales linearly withwavelength which squares the peak radiant exposure within the focalplane. Second, the linear absorption of the material itself allows aneven lower threshold for plasma formation or low densityphotodecomposition as initially more laser energy is absorbed in thetarget structure. Third, the use of UV laser pulses in the nanosecondand sub-nanosecond regime enables linear absorption enhancedphotodecomposition and chromophore guided ionization.

Furthermore, this chromophore-guided ionization when using ultravioletwavelength strongly lowers the threshold for ionization in case ofplasma formation as well lowers the threshold for low densityphotodecomposition for material modification or alteration withoutcavitation even under very weak absorption. The linear absorption alsoallows for the specific treatment of topical lens structures (e.g. thelens capsule) as the optical penetration depth of the laser beam islimited by the linear absorption of the lens. This is especially truefor aged lenses which absorption in the UV-blue spectral regionincreases strongly compared to young lenses.

The laser assembly 12 can include control and conditioning components.For example, such control components can include components such as abeam attenuator to control the energy of the laser pulse and the averagepower of the pulse train, a fixed aperture to control thecross-sectional spatial extent of the beam containing the laser pulses,one or more power monitors to monitor the flux and repetition rate ofthe beam train and therefore the energy of the laser pulses, and ashutter to allow/block transmission of the laser pulses. Suchconditioning components can include an adjustable zoom assembly and afixed optical relay to transfer the laser pulses over a distance whileaccommodating laser pulse beam positional and/or directionalvariability, thereby providing increased tolerance for componentvariation.

In many embodiments, the laser assembly 12 and the confocal detectionassembly 14 have fixed positions relative to the base assembly 26. Thebeam 28 emitted by the laser assembly 12 propagates along a fixedoptical path through the confocal detection assembly 14 to the sharedoptics 16. The beam 28 propagates through the shared optics 16 along avariable optical path 30, which delivers the beam 28 to the scanningassembly 18. In many embodiments, the beam 28 emitted by the laserassembly 12 is collimated so that the beam 28 is not impacted by patientmovement induced changes in the length of the optical path between thelaser assembly 12 and the scanner 16. The scanning assembly 18 isoperable to scan the beam 28 (e.g., via controlled variable deflectionof the beam 28) in at least one dimension. In many embodiments, thescanning assembly 18 is operable to scan the beam 28 in two dimensionstransverse to the direction of the propagation of the beam 28 and isfurther operable to scan the location of a focal point of the beam 28 inthe direction of propagation of the beam 28. The scanned beam is emittedfrom the scanning assembly 18 to propagate through the objective lensassembly 20, through the interface device 22, and to the patient 24.

The shared optics 16 is configured to accommodate a range of movement ofthe patient 24 relative to the laser assembly 12 and the confocaldetection assembly 14 in one or more directions while maintainingalignment of the beam 28 emitted by the scanning assembly 18 with thepatient 24. For example, in many embodiments, the shared optics 16 isconfigured to accommodate a range movement of the patient 24 in anydirection defined by any combination of unit orthogonal directions (X,Y, and Z).

The shared optics 16 supports the scanning assembly 18 and provides thevariable optical path 30, which changes in response to movement of thepatient 24. Because the patient interface device 22 is interfaced withthe patient 24, movement of the patient 24 results in correspondingmovement of the patient interface device 22, the objective lens assembly20, and the scanning assembly 18. The shared optics 16 can include, forexample, any suitable combination of a linkage that accommodatesrelative movement between the scanning assembly 18 and, for example, theconfocal detection assembly 24, and optical components suitably tied tothe linkage so as to form the variable optical path 30.

A portion of the electromagnetic radiation beam 28 that is reflected byeye tissue at the focal point propagates back to the confocal detectionassembly 14. Specifically, a reflected portion of the electromagneticradiation beam 28 travels back through the patient interface device 22,back through the objective lens assembly 20, back through (andde-scanned by) the scanning assembly 18, back through the shared optics16 (along the variable optical path 30), and to the confocal detectionassembly 14. In many embodiments, the reflected portion of theelectromagnetic radiation beam that travels back to the confocaldetection assembly 14 is directed to be incident upon a sensor thatgenerates an intensity signal indicative of intensity of the incidentportion of the electromagnetic radiation beam. The intensity signal,coupled with associated scanning of the focal point within the eye, canbe processed in conjunction with the parameters of the scanning to, forexample, image/locate structures of the eye, such as the anteriorsurface of the cornea, the posterior surface of the cornea, the iris,the anterior surface of the lens capsule, and the posterior surface ofthe lens capsule. In many embodiments, the amount of the reflectedelectromagnetic radiation beam that travels to the confocal detectionassembly 14 is substantially independent of expected variations in thelength of the variable optical path 30 due to patient movement, therebyenabling the ability to ignore patient movements when processing theintensity signal to image/locate structures of the eye.

FIG. 2 schematically illustrates details of an embodiment of the lasersurgery system 10. Specifically, example configurations areschematically illustrated for the laser assembly 12, the confocaldetection assembly 14, and the scanning assembly 18. As shown in theillustrated embodiment, the laser assembly 12 can include an laser 32(e.g., a femtosecond laser), alignment mirrors 34, 36, a beam expander38, a one-half wave plate 40, a polarizer and beam dump device 42,output pickoffs and monitors 44, and a system-controlled shutter 46. Theelectromagnetic radiation beam 28 output by the laser 32 is deflected bythe alignment mirrors 34, 36. In many embodiments, the alignment mirrors34, 36 are adjustable in position and/or orientation so as to providethe ability to align the beam 28 with the downstream optical paththrough the downstream optical components. Next, the beam 28 passesthrough the beam expander 38, which increases the diameter of the beam28. Next, the expanded beam 28 passes through the one-half wave plate 40before passing through the polarizer. The beam exiting the laser islinearly polarized. The one-half wave plate 40 can rotate thispolarization. The amount of light passing through the polarizer dependson the angle of the rotation of the linear polarization. Therefore, theone-half wave plate 40 with the polarizer acts as an attenuator of thebeam 28. The light rejected from this attenuation is directed into thebeam dump. Next, the attenuated beam 28 passes through the outputpickoffs and monitors 44 and then through the system-controlled shutter46. By locating the system-controlled shutter 46 downstream of theoutput pickoffs and monitors 44, the power of the beam 28 can be checkedbefore opening the system-controlled shutter 46.

As shown in the illustrated embodiment, the confocal detection assembly14 can include a polarization-sensitive device such as a polarized orunpolarized beam splitter 48, a filter 50, a focusing lens 51, a pinholeaperture 52, and a detection sensor 54. A one-quarter wave plate 56 isdisposed downstream of the polarized beam splitter 48. The beam 28 asreceived from the laser assembly 12 is polarized so as to pass throughthe polarized beam splitter 48. Next, the beam 28 passes through theone-quarter wave plate 56, thereby rotating the polarization axis of thebeam 28. A quarter rotation is a presently preferred rotation amount.After reflecting from the focal point in the eye, the returningreflected portion of the beam 28 passes back through the one-quarterwave plate 56, thereby further rotating the polarization axis of thereturning reflected portion of the beam 28. Ideally, after passing backthrough the one-quarter wave plate 56, the returning reflected portionof the beam has experienced a total polarization rotation of 90 degreesso that the reflected light from the eye is fully reflected by thepolarized beam splitter 48. The birefringence of the cornea can also betaken into account if, for example, the imaged structure is the lens. Insuch a case, the plate 56 can be adjusted/configured so that the doublepass of the plate 56 as well as the double pass of the cornea sum up toa polarization rotation of 90 degrees. Because the birefringence of thecornea may be different from patient to patient, theconfiguration/adjustment of the plate 56 can be done dynamically so asto optimize the signal returning to the detection sensor 54.Accordingly, the returning reflected portion of the beam 28 is nowpolarized to be at least partially reflected by the polarized beamsplitter 48 so as to be directed through the filter 50, through the lens51, and to the pinhole aperture 52. The filter 50 can be configured toblock wavelengths other than the wavelengths of interest. The pinholeaperture 52 is configured to block any returning reflected portion ofthe beam 28 reflected from locations other than the focal point fromreaching the detection sensor 54. Because the amount of returningreflected portion of the beam 28 that reaches the detection sensor 54depends upon the nature of the tissue at the focal point of the beam 28,the signal generated by the detection sensor 54 can be processed incombination with data regarding the associated locations of the focalpoint so as to generate image/location data for structures of the eye.

In this embodiment, the same laser assembly may be used both fortreatment (i.e., modification) and imaging of the target tissue. Forinstance, the target tissue may be imaged by raster scanning pulsedlaser beam 28 along the target tissue to provide for a plurality of datapoints, each data point having a location and intensity associated withit for imaging of the target tissue. In some embodiments, the rasterscan is selected to deliver a sparse pattern in order to limit thepatient's exposure, while still discerning a reasonable map of theintraocular targets. In order to image the target tissue, the treatmentlaser beam (i.e. the laser beam having the parameters suitably chosen asdescribed above for the modification of tissue) is preferably attenuatedto the nanoJoule level for imaging of the structures to be treated. Whenused for imaging, the attenuated laser beam may be referred to as animaging beam. In many embodiments, the treatment beam and the imagingbeam may be the same except that the pulse energy of the laser source islower than the treatment beam when the laser beam is used for imaging.In many embodiments, the pulse energy of the laser beam when used forimaging is preferably from about 0.1 nJ to 10 nJ, preferably less than 2nJ and more preferably less than 1.8 nJ. The use of the same laser beamfor both treatment and imaging provides for the most direct correlationbetween the position of the focal locations for imaging andtreatment—they are the same beam. This attenuated probe beam can ispreferably used directly in a back reflectance measuring configuration,but, alternatively, may be used indirectly in a fluorescence detectionscheme. Since increases in both backscatter and fluorescence withintissue structures will be evident, both approaches have merit.

In a preferred embodiment, imaging of a first target area to be modifiedis performed sequentially with the modification of the tissue in thefirst target area before moving on to a second, different, target area,i.e. imaging is performed sequentially with treatment in a predeterminedtarget area. Thus, for instance imaging of the lens capsule ispreferably followed by treatment of the lens capsule before imaging iscarried out on other either structures, such as the cornea or iris. Inanother embodiment, imaging of a first target area where a firstincision to be place is performed sequentially with the scanning thetreatment beam to perform the incision in the first target area beforemoving on to a second target area for performing a second incision, i.e.imaging of the area to be incised is performed sequentially withscanning the treatment beam to perform in the predetermined target area.In another embodiment, a cataract procedure comprises a capsulotomyincision, and at least one of a cataract incision and a limbal relaxingincision. In one embodiment, imaging of the target tissue where thecapsulotomy is to be performed is followed by scanning of the treatmentto perform the capsulotomy, and then the treatment beam is scanned toperform the capsulotomy. Subsequently, imaging of the target tissuewhere the at least one of the cataract incisions (CI) and the limbalrelaxing incision (LRI) is carried out and then the treatment beam isscanned to perform the at least one of the LRI and the CI. When an LRIis selected, this minimizes the chance for the patient to move betweenimaging and treatment for the LRIs which are the most critical/sensitiveto eye movements between image and treatment.

As shown in the illustrated embodiment, the scanning assembly 18 caninclude a z-scan device 58 and a xy-scan device 60. The z-scan device 58is operable to vary a convergence/divergence angle of the beam 28 andthereby change a location of the focal point in the direction ofpropagation of the beam 28. For example, the z-scan device 58 caninclude one or more lenses that are controllably movable in thedirection of propagation of the beam 28 to vary a convergence/divergenceangle of the beam 28. The xy-scan device 60 is operable to deflect thebeam 28 in two dimensions transverse to the direction of propagation ofthe beam 28. For example, the xy-scan device 60 can include one or moremirrors that are controllably deflectable to scan the beam 28 in twodimensions transverse to the direction of propagation of the beam 28.Accordingly, the combination of the z-scan device 58 and the xy-scandevice 60 can be operated to controllably scan the focal point in threedimensions, for example, within the eye of the patient.

As shown in the illustrated embodiment, a camera 62 and associated videoillumination 64 can be integrated with the scanning assembly 18. Thecamera 62 and the beam 28 share a common optical path through theobjective lens assembly 20 to the eye. A video dichroic 66 is used tocombine/separate the beam 28 with/from the illumination wavelengths usedby the camera. For example, the beam 28 can have a wavelength of about355 nm and the video illumination 64 can be configured to emitillumination having wavelengths greater than 450 nm. Accordingly, thevideo dichroic 66 can be configured to reflect the 355 nm wavelengthwhile transmitting wavelengths greater than 450 nm.

FIG. 3 schematically illustrates a laser surgery system 300 according tomany embodiments. The laser surgery system 300 includes the laserassembly 12, the confocal detection assembly 14, the shared optics 16,the scanning assembly 18, the objective lens assembly 20, the patientinterface 22, communication paths 302, control electronics 304, controlpanel/graphical user interface (GUI) 306, and user interface devices308. The control electronics 304 includes processor 310, which includesmemory 312. The patient interface 22 is configured to interface with apatient 24. The control electronics 304 is operatively coupled via thecommunication paths 302 with the laser assembly 12, the confocaldetection assembly 14, the shared optics 16, the scanning assembly 18,the control panel/GUI 306, and the user interface devices 308.

The scanning assembly 18 can include a z-scan device and a xy-scandevice. The laser surgery system 300 can be configured to focus theelectromagnetic radiation beam 28 to a focal point that is scanned inthree dimensions. The z-scan device can be operable to vary the locationof the focal point in the direction of propagation of the beam 28. Thexy-scan device can be operable to scan the location of the focal pointin two dimensions transverse to the direction of propagation of the beam28. Accordingly, the combination of the z-scan device and the xy-scandevice can be operated to controllably scan the focal point of the beamin three dimensions, including within a tissue of the patient 24 such aswithin an eye tissue of the patient 24. The scanning assembly 18 issupported by the shared optics 16, which may be configured toaccommodate patient movement induced movement of the scanning assembly18 relative to the laser assembly 12 and the confocal detection assembly14 in three dimensions. The patient interface 22 is coupled to thepatient 24 such that the patient interface 22, the objective lensassembly 20, and the scanning assembly 18 move in conjunction with thepatient 24. For example, in many embodiments, the patient interface 22employs a suction ring that is vacuum attached to an eye of the patient24. The suction ring can be coupled with the patient interface 22, forexample, using vacuum to secure the suction ring to the patientinterface 22.

The control electronics 304 controls the operation of and/or can receiveinput from the laser assembly 12, the confocal detection assembly 14,the free-floating assembly 16, the scanning assembly 18, the patientinterface 22, the control panel/GUI 306, and the user The interfacedevices 308 via the communication paths 302. The communication paths 302can be implemented in any suitable configuration, including any suitableshared or dedicated communication paths between the control electronics304 and the respective system components. The control electronics 304can include any suitable components, such as one or more processors, oneor more field-programmable gate arrays (FPGA), and one or more memorystorage devices. In many embodiments, the control electronics 304controls the control panel/GUI 306 to provide for pre-procedure planningaccording to user specified treatment parameters as well as to provideuser control over the laser eye surgery procedure.

The control electronics 304 can include a processor/controller 310 thatis used to perform calculations related to system operation and providecontrol signals to the various system elements. A computer readablemedium 312 is coupled to the processor 310 in order to store data usedby the processor and other system elements. The processor 310 interactswith the other components of the system as described more fullythroughout the present specification. In an embodiment, the memory 312can include a look up table that can be utilized to control one or morecomponents of the laser system surgery system 300. The processor 310 canbe a general purpose microprocessor configured to execute instructionsand data, such as a Pentium processor manufactured by the IntelCorporation of Santa Clara, Calif. It can also be an ApplicationSpecific Integrated Circuit (ASIC) that embodies at least part of theinstructions for performing the method according to the embodiments ofthe present disclosure in software, firmware and/or hardware. As anexample, such processors include dedicated circuitry, ASICs,combinatorial logic, other programmable processors, combinationsthereof, and the like memory 312 can be local or distributed asappropriate to the particular application. Memory 312 can include anumber of memories including a main random access memory (RAM) forstorage of instructions and data during program execution and a readonly memory (ROM) in which fixed instructions are stored. Thus, thememory 312 provides persistent (non-volatile) storage for program anddata files, and may include a hard disk drive, flash memory, a floppydisk drive along with associated removable media, a Compact Disk ReadOnly Memory (CD-ROM) drive, an optical drive, removable mediacartridges, and other like storage media.

The user interface devices 308 can include any suitable user inputdevice suitable to provide user input to the control electronics 304.For example, the user interface devices 308 can include devices such as,for example, a touch-screen display/input device, a keyboard, afootswitch, a keypad, a patient interface radio frequency identification(RFID) reader, an emergency stop button, and a key switch.

Certain acts or steps in connection with the methods and systems ofverifying the location of a laser scan in an object, preferably an eyeare shown in FIG. 2. In some embodiments, the object is an eye and themethods and acts of verifying the locations of the laser scan isoperable to verify the location of an incision in ocular surgicalprocedures, including cataract surgery. In other embodiments, the objectis a calibration apparatus, and the methods and acts are operable toverify the calibration of a laser surgical system, preferably a lasereye surgical system.

The methods and/or acts of verifying the location of a laser scan withinan object include, at Step 202 (FIG. 4), imaging the object, theresulting image including a portion of the object at a predeterminedlocation to be scanned. The type or manner of imaging is notparticularly limited, so long as the selected imaging method is capableof imaging the portion of the object in which the predetermined scanlocation is located. In many embodiments, the predetermined scanlocation includes the location of an incision that has been prescribedor identified by a health professional for placement in a tissue of theeye, such as the lens capsule, the lens, the cornea or the limbus. Inthis case, the selected imaging method should be capable of imaging theselected tissue. In one embodiment, the imaging method is opticalimaging by a camera, and the image is presented as an en face image ofthe eye on monitor as shown in FIG. 5. The image may likewise be a videoimage in which successive images are captured in real time by a sensorand displayed on a monitor. The monitor may operate at, for instance, 60Hz, 120 Hz or 240 Hz.

In another embodiment, the imaging method includes scanning the locationof a focal point of a pulsed laser beam and confocally detecting lightreflected from the location of the pulsed laser. Preferably, the pulsedlaser beam is an ultraviolet pulsed laser beam having a wavelength of320-370 nm. In many embodiments, the methods of verifying the locationof a laser scan within an object include both video imaging and confocalimaging.

The methods and/or acts of verifying the location of a laser scan withinan object include, at Step 204, identifying an expected scan locationwithin the image corresponding to the predetermined scan location. Inmany embodiments, a camera 62 in the imaging system includes a sensorhaving an orthogonal array of pixels (e.g., in x and y directions wherethe corresponding z direction is in the direction of propagation of theelectromagnetic radiation beam). Thus, in many embodiments, the image iscomprised of an array of pixels, preferably color pixels. In manyembodiments, a calibration of the system, according to the methodsdescribed herein, provide a known relationship between the location of apixel in the orthogonal array of the image and a location of the tissuein the treatment space. This known correspondence between the pixels inthe image and a location in treatment space makes it possible toidentify an expected scan location in the image corresponding to thepredetermined scan location. In many embodiments, the expected scanlocation within the image is a set of pixels, PEL illustrated visuallyin FIG. 5 (not to scale), that is a subset of the array of pixelscomprising the image. The set of pixels, PEL, may include a pixeldenominated as an expected starting point pixel of the expected scanlocation, Pstart, a pixel may be identified as an expected ending pointpixel, Pend, of the expected scan location or a pixel denominated as amidpoint pixel, Pmid, located at some position between the startingpoint pixel and the ending point pixel.

The methods and/or acts of verifying the location of a laser scan withinan object include, at Step 206, conducting a laser scan of the object byscanning a focal point of the laser beam through at least a portion ofthe object. The location of the scan is not particularly limited;however, in many embodiments, it will preferably include thepredetermined scan location. The laser beam is preferably a pulsed laserbeam, and preferably a pulsed ultraviolet laser beam. The laser scan ispreferably a raster scan of the pulsed laser beam. In some embodiments,the laser beam may be of sufficient energy to modify the eye tissuescanned, and such that a succession of laser pulses within the eyetissue is sufficient to incise the tissue scanned. In other embodiments,the energy of the laser beam will be insufficient to modify the tissuescanned. The intensity of the laser beam is also preferably insufficientto cause the formation of a plasma, and also preferably insufficient togenerate one or more cavitation events, such as the formation of abubble.

The methods and/or acts of verifying the location of a laser scan withinan object include, at Step 208, detecting the luminescence regionscanned by the laser beam. As would be understood by those ordinarilyskilled, individual photons of the ultraviolet laser beam, each havingan energy, hν, will be absorbed by various components in the tissuescanned. This absorbed light will then be re-emitted by the component asa photon of lower energy (larger wavelength) either by fluorescence orphosphorescence from the scanned tissue. When ultraviolet light is usedfor the laser scan, the emitted luminescence generally includes light inthe blue, indigo and violet portions of the visible spectrum, havingwavelengths from about 400 nm to 475 nm. The emission of light fromtissue, including by processes such as fluorescence or phosphorescence,is generally referred to herein as luminescence. In many embodiments,the luminescence, preferably in the range of 400 nm to 475 nm light isdetected using the same camera 62 and same sensor having the orthogonalarray of pixels which was used to image an object.

The methods and/or acts of verifying the location of a laser scan withinan object include, at Step 208, detecting the luminescence from theregion scanned by the laser beam. As would be understood by thoseordinarily skilled, each pixel has red (R), Green (G) and Blue (B)components (“R, G, B components”), each having an intensity, I,associated with it that has a value from Imin to Imax. In manyembodiments, Imin=0 and Imax=255. According to some embodiments, theactual scanned location within the image may be determined monitoringthe intensity, IB, of the B component of the pixels that make up theimage. In many embodiments, the actual scanned location may be comprisedof one or more Pixels, Pact in the image. In many embodiments, a pixel,Pact, is identified as being an actual scanned location if the measuredvalue of Ib for the pixel is greater than a predetermined thresholdvalue, Ip. More than one Pact may be identified in one image or frame.The predetermined threshold value may be empirically determined based onthe object to be imaged. For instance, if the object to be imagedcontains very few blue components, it may be possible to determineluminescence based on a relatively small Ib. In contrast, if the objectto be imaged contains a relatively large amount of blue components, itmay be necessary to determine luminescence based on a relatively largeIB. Those skilled in the art thus instructed can suitably determine thenecessary threshold for each application. In some embodiments, thepredetermined threshold value, Ip, may be 0.9 Imax, 0.8 Imax, 0.7 Imax,0.6 Imax, 0.5 Imax, 0.4 Imax, 0.3 Imax, 0.2 Imax, or 0.1 Imax. This maybe termed a “pixel thresholding” approach.

In other embodiments, the actual scanned location within the image maybe determined by comparing the intensity, IB, of the B component of apixel in successive images or frames an image. In this embodiment, theactual scanned location is determined by calculating a differencebetween an Ib value of a pixel in a first frame, Ib1, and the Ib valueof the same pixel in a second successive frame, Ib2. In manyembodiments, a pixel is identified as being an actual scanned locationif the measured value difference, Ib2−Ib1 for a pixel is greater than apredetermined threshold value, IP. The predetermined threshold value maybe empirically determined based on the object to be imaged; however,since the identification is based on a difference in the same pixel insuccessive frames, the threshold may not be as sensitive to the amountof blue in the components of the image. In some embodiments, thepredetermined threshold value, Ip, may be 0.9 Imax, 0.8 Imax, 0.7 Imax,0.6 Imax, 0.5 Imax, 0.4 Imax, 0.3 Imax, 0.2 Imax, or 0.1 Imax. This maybe termed a “consecutive differential” approach.

In other embodiments, the actual scanned location within the image maybe determined by comparing an intensity, IB, of the B component of apixel in a first frame or image and then calculating a difference inintensity value for the pixel in each successive image or frame comparedto its intensity of the first frame. In this embodiment, the actualscanned location is determined by comparing an Ib value of a pixel in afirst frame, Ib1, with the Ib value of the same pixel in each successivei=2, n frames, i.e. Ib2 Ib3, Ib4 . . . Ibn etc. In many embodiments, apixel is identified as being an actual scanned location if the measuredvalue difference, Ibi−Ib1 for a pixel is greater than a predeterminedthreshold value, IP. The predetermined threshold value may beempirically determined based on the object to be imaged; however, sincethe identification is based on a difference in the same pixel insuccessive frames, the threshold may not be as sensitive to the amountof blue in the components of the image. In some embodiments, thepredetermined threshold value, Ip, may be 0.9 Imax, 0.8 Imax, 0.7 Imax,0.6 Imax, 0.5 Imax, 0.4 Imax, 0.3 Imax, 0.2 Imax, or 0.1 Imax. This maybe termed an “absolute differential” approach.

In some embodiments, a statistical approach may be implemented fordetermining the actual scanned location within the image. In theseprobabilistic approaches, the values for the intensity, IB of thethresholding approach, the value of Ib2−Ib1 in the consecutivedifferential approach and the value Ibi−Ib1 in the absolute differentialis assigned a probability of being an actual scanned location, and isdetermined to be an actual scanned location if the value of theprobability is greater than a predetermined probability, for instance50% (i.e., 0.5), or 60%, 70%, 80% or 90%.

Since a scan is conducted over a period of time, the pixels which areidentified as being an actual scanned location, Pact, may change duringthe time course of the scan. Analysis, such as by overlaying successiveframes or obtaining difference images between frames, either ofindividual pairs of frames or of all successive images/frames during thescan permits the determination of all the actual scanned locations andof the direction of the scan during the scan. In some embodiments, allactual scanned locations may be determined before a comparison of theactual scanned location with the expected scan location is completed.

The methods and/or acts of verifying the location of a laser scan withinan object include, at Step 214, providing a warning if a differencebetween the actual location in the image and an expected scan locationin the image is greater than a threshold distance, DT. The nature of thewarning is not particularly limited. For instance, a warning message maybe placed on the image indicating a difference in the expected scanlocation and actual scan location has been detected. The warning mayoptionally include stopping the scan and alerting a user. Where theobject is an eye, the warning may also optionally include reducing theintensity of the laser beam below a level necessary to incise thetissue.

The manner of calculating the difference between the expected scanlocation and the actual scan location is not particularly limited. Inmany embodiments, the calculated difference may be a distance betweenthe expected scan location and the actual scanned location. The distancemay be between any of the one or more pixels, Pact, identified as anactual scan location and any pixel from the set of pixels, PEL, whichcomprises the expected scan locations. In some embodiments, one Pactfrom the actual scan locations is selected for the distance measurementand one pixel is selected from the set of PEL pixels for the distancemeasurements. In some embodiments, the selected expected scan locationpixel may be either Pstart, Pend or a Pmid. The distance may becalculated as a number of pixels separating the selected pixels.Alternatively, the distance may be calculated as a physical distance in,for instance, units of microns. In another alternative, it may besuitable to calculate the distance as an angular distance between thepixels, for instance, by an angle theta, θ, around an axis centered atthe pupil center in the direction of propagation of the laser lightsource. The threshold difference, DT, may be chosen based on the unitsselected. In the case of a distance measured in microns, the thresholddifference DT, may be 5000 microns, or 1000 microns, or 500 microns or200 microns or 100 microns, or 50 microns or 5 microns. In the case ofangular distance, the distance DT, may be 120°, or 90°, or 60°, or 45°,or 30°, or 15°.

The methods and/or acts of verifying the location of a laser scan may beused in connection with laser eye surgery systems and methods to verifythe placement of one or more ocular incisions, including in methods forcataract surgery using a laser eye surgery system for verifying theplacement of incisions in a cataract surgery. The laser eye surgerysystem may be the one shown in FIGS. 1-3 and described herein. Thus,some embodiments are a laser surgical system configured to carry out themethods described herein. In some embodiments, a user or physician willdefine one or more incisions to be performed by the laser surgicalsystem during cataract surgery selected from capsulotomy incisions,primary incisions, sideport incisions and arcuate incisions by enteringthe necessary parameters into system to define the incision. The lasersurgical system is configured to receive those parameters, image theeye, identify the expected scan location within the image correspondingto the selected incisions, conduct a laser scan of the eye by scanningthe focal point of a laser beam, detect luminescence from the regionscanned, identify the actual scanned location within the image based onthe detected luminescence, and provide a warning to the user if thedifference between the expect location in the image and the actuallocation in the image is greater than a predetermined threshold. In someembodiments, the laser scan that is conducted is a confocal imaging scanof the eye to verify that the confocal imaging scan is imaging theactual location to be incised. In some embodiment, the laser scanconducted is a treatment scan of sufficient energy to incise the tissueto be treated. In other embodiments, the scan conducted is the same asthe treatment scan but at energies insufficient to incise human tissue.This scan can be done in order to verify the placement of the incisionsprior to conducting a treatment scan capable of incising tissue.

The methods and/or acts of verifying the location of a laser scan may beused in connection with laser eye surgery systems and methods to verifythe calibration of an eye surgical system prior to treatment. Themethods or acts of verifying the calibration may include a calibrationapparatus 300 shown in FIGS. 6A and 6B. The calibration apparatus 300includes sidewall 320 and also comprises structures similar tostructures of an eye. For example, the calibration apparatus 300 mayinclude a container 350 having a viscous substance or solid substancethat is similarly optically transmissive to the structures of the eye.The material 350 may comprise of visco-elastic fluid, a gel or otheroptically transmissive structure and material, for example. Thecalibration apparatus 300 comprises an iris structure 310 and,optionally, a lens structure 330, either of which can provide a suitablesurface for calibration. At least one of the surfaces of lens structure330 or iris structure 310 should emit blue wavelength light whenirradiated by ultraviolet light. Here, a structure or property is“similar” if it is within 10%, preferably within 5% and more preferablywithin about 1% of a typical measurement of that structure or propertyin an adult human eye. The calibration structure 300 may connect to thepatient interface as described herein and a fluid (note shown) can beprovided above the calibration apparatus, for example.

A method and/or acts of verifying the calibration of laser surgicalsystem, including a laser eye surgical system, include imaging acalibration apparatus, identifying an expected scan location within theimage corresponding to a predetermined scan pattern within thecalibration apparatus, conducting a laser scan of the calibrationapparatus by scanning the focal point of a laser beam, detectingluminescence from the region of the calibration area scanned,identifying the actual scanned location within the image based on thedetected luminescence, and identifying the laser surgical system as notcalibrated if a difference between the expected scan location in theimage and the actual location in the image is greater than apredetermined threshold. The method can also include identifying thelaser surgical system as calibrated if a difference between the expectedscan location in the image and the actual location in the image is lessthan a predetermined threshold.

System Calibration

In many embodiments, a calibration of the system is carried out toprovide a known relationship between the location of a pixel in theorthogonal array of the image and a location of the tissue in thetreatment space. This known correspondence between the pixels in theimage and a location in treatment space makes it possible to identify anexpected scan location in the image corresponding to the predeterminedscan location, an actual scanned location of a laser scan in the imageand a difference between the actual scanned location and the expectedscan location. The method for performing the calibration is notparticularly limited. Examples of suitable calibration methods can befound, for instance, in U.S. patent application Ser. No. 14/069,703,filed Nov. 1, 2013, entitled “Laser Surgery System Calibration,” andU.S. patent application Ser. No. 14/191,095, filed Feb. 26, 2014, theentire contents of which are hereby incorporated by reference herein inits entirety.

In brief, the laser surgery system 10 can be calibrated to relatelocations in a treatment space with pixels in the camera 62 and withcontrol parameters used to control the scanning assembly 18 such thatthe focal point of the electromagnetic radiation beam can be accuratelypositioned within the intraocular target. Such calibration can beaccomplished at any suitable time, for example, prior to using the lasersurgery system 10 to treat a patient's eye.

FIG. 7A is a top view diagram of a calibration plate 402 that can beused to calibrate the laser surgery system 10. In many embodiments, thecalibration plate 402 is a thin plate having an array of targetfeatures, for example, through holes 404 therein. In alternateembodiments, the calibration plate 402 is a thin plate having a field ofsmall dots as the target features. While any suitable arrangement of thetarget features can be used, the calibration plate 402 of FIG. 7A has anorthogonal array of through holes 404. Any suitable number of the targetfeatures can be included in the calibration plate 402. For example, theillustrated embodiment has 29 rows and 29 columns of the through holes404, with three through holes at each of the four corners of thecalibration plate 402 being omitted from the orthogonal array of throughholes 404.

In many embodiments, each of the through holes 404 is sized small enoughto block a suitable portion of an electromagnetic radiation beam whenthe focal point of the electromagnetic radiation beam is not located atthe through hole. For example, each of the through holes 404 can have adiameter slightly greater than the diameter of the focal point of theelectromagnetic radiation beam so as to not block any of theelectromagnetic radiation beam when the focal point is positioned at oneof the through holes 404. In the embodiment shown, the through holes 404have a diameter of 5 which is sized to be used in conjunction with afocal point diameter of 1 μm.

FIG. 7B schematically illustrates using the calibration plate 402 tocalibrate the camera 62 of the laser surgery system 10. The calibrationplate 402 is supported at a known fixed location relative to theobjective lens assembly 20. In many embodiments, the objective lensassembly 20 is configured for telecentric scanning of theelectromagnetic radiation beam and the calibration plate 402 issupported to be perpendicular to the direction of propagation of theelectromagnetic radiation beam. The calibration plate 402 is disposedbetween the objective lens assembly 20 and a light source 406. The lightsource 406 is used to illuminate the calibration plate 402. A portion ofthe illumination light from the light source 406 passes through each ofthe through holes 404, thereby producing an illuminated location withinthe field of view of the camera 62 at each of the through holes 404. Alight beam 408 from each of the through holes 404 passes through theobjective lens assembly 20, through the video dichroic 66, an into thecamera 62. In many embodiments, the camera 62 includes a sensor havingan orthogonal array of pixels (e.g., in x and y directions where thecorresponding z direction is in the direction of propagation of theelectromagnetic radiation beam). In many embodiments, X and Y pixelvalues for each of the light beams 408 is used in conjunction with theknown locations of the through holes 404 relative to the objective lensassembly 20 to determine the relationship between the camera X and Ypixel values and locations in the treatment space for dimensionstransverse to the propagation direction of the electromagnetic radiationbeam.

FIG. 7C schematically illustrates using the calibration plate 402 tocalibrate the scanning assembly 18. The calibration plate 402 issupported at a known fixed location relative to the objective lensassembly 20. In many embodiments, the objective lens assembly 20 isconfigured for telecentric scanning of the electromagnetic radiationbeam and the calibration plate 402 is supported to be perpendicular tothe direction of propagation of the electromagnetic radiation beam. Thecalibration plate 402 is disposed between the objective lens assembly 20and a detector 410. The detector 410 is configured to generate a signalindicative of how much of the electromagnetic radiation beam is incidentthereon, thereby being indirectly indicative of how much of theelectromagnetic radiation beam is blocked by the calibration plate 402.For example, when the focal point of the electromagnetic radiation beamis positioned at one of the through holes 404 (as illustrated for thefocal point disposed on the right side of the detection plate 402 inFIG. 7B), a maximum amount of the electromagnetic radiation beam passesthrough the through hole and is incident on the detector 410. Incontrast, when the focal point of the electromagnetic radiation beam isnot positioned at one of the through holes 404 (as illustrated for thefocal point disposed above the left side of the detection plate 402 in,a portion of the electromagnetic radiation beam is blocked from reachingthe detector 410.

Control parameters for the z-scan device 58 and the xy scan device 60are varied to locate the focal point of the electromagnetic radiationbeam at each of a suitable set of the through holes, thereby providingdata used to determine the relationship between the control parametersfor the scanning assembly 18 and the resulting location of the focalpoint of the electromagnetic radiation beam. The z-scan device 58 isoperable to vary a convergence/divergence angle of the electromagneticradiation beam, thereby being operable to control the distance of thefocal point from the objective lens in the direction of propagation ofthe electromagnetic radiation beam. The xy-scan device 60 is operable tovary a direction of the electromagnetic radiation beam in twodimensions, thereby providing the ability to move the focal point in twodimensions transverse to the direction of propagation of theelectromagnetic radiation beam.

A suitable existing search algorithm can be employed to vary the controlparameters for the z-scan device 58 and the xy-scan device 60 so as toreposition the focal point to be located at each of a suitable set ofthe through holes 404. In many embodiments where the objective lensassembly 20 is configured to telecentrically scan the electromagneticradiation beam, the resulting control parameter data for the scanningassembly 18 can be used to calibrate the scanning assembly 18 relativeto directions transverse to the direction of propagation of theelectromagnetic radiation beam (e.g., x and y directions transverse to az direction of propagation of the electromagnetic radiation beam).

Application to Cataract Surgery

In many embodiments, the methods and/or acts of verifying the locationof a laser scan is used with laser eye surgery systems and methods toverify the placement of one or more ocular incisions. In manyembodiments, the methods and/or acts are used in cataract surgery usinga laser eye surgery system for verifying the placement of incisions in acataract surgery.

In cataract surgery, a capsulotomy incision, often in the form of asmall round hole is formed in the anterior side of the lens capsule toprovide access to the lens nucleus.

In addition, cataract surgery may include three types of corneaincisions: arcuates, primaries and sideports. Parameters that may beused to define the capsulotomy include shape (i.e. circular, elliptical,rectangular or polygonal) and size. The systems described herein aredesigned to receive these parameters based on user or physician's inputand preferably, to provide a prompt for their input where not received.

Primary incisions and sideport incisions may have the same structure.They are generally multiplanar structures that create an opening thatallow the physician access into the anterior chamber. The primaries areused for insertion of the aspiration tool and the insertion of the IOL.Sideport incisions may be used for inserting smaller instrumentationinto the anterior chamber. The location and shape of both the primaryincisions and the sideport incisions are determined by the userparameters and, optionally, by information from a section scan asdescribed herein, where the cornea anterior and posterior surfaces maybe modeled by circles. The anterior and posterior curvatures of thecornea as measured in the circular fits of the section scans mayoptionally be used to position the cuts. Parameters that may be used todefine the primary cataract incision or the sideport incision arepreferably selected from the group consisting of limbus offset, width,side cut angle, plane depth and length. The systems described herein aredesigned to receive these parameters based on user or physician's inputand preferably, to provide a prompt for their input where they are notreceived.

Arcuate incisions may be used to correct a patient's astigmatism. Forinstance, they may adjust the curvature of the cornea to a morespherical shape by means relaxing stresses along the meridian on whichthey are placed. They are parts of a conical surface that crosses boththe anterior and posterior surfaces of the cornea. In some embodiments,the anterior curvature and posterior curvature of the cornea, asmeasured in a circular fit to a section scan, are used to position an“along-the-cut” scan. The along-the-cut scan lays on the surface of acone that transverses the cornea. The arcuate incision can be locatedwithin the along-the-cut scan. Parameter that may be used to define thearcuate incision may include the size of the optical zone, arc length,uncut anterior portion, uncut posterior portion and side cut angle. Thesystems described herein are designed to receive these parameters basedon user or physician's input and preferably, to provide a prompt fortheir input where not received.

Capsulotomy Incisions

The laser surgery system 10 can be used to form any suitably shapedcapsulotomy. For example, while the anterior and posterior capsulotomiesin the illustrated embodiments are circular, any other suitable shape,including but not limited to, elliptical, rectangular, and polygonal canbe formed. And the anterior and/or posterior capsulotomy can be shapedto accommodate any correspondingly suitably shaped IOL.

For example, referring now to FIG. 8, the laser surgery system 10 can beused to incise an anterior capsulotomy and/or a posterior capsulotomy inthe anterior portion of a lens capsule 418. The focal point of theelectromagnetic radiation beam can be scanned to form an anteriorcapsulotomy closed incision boundary surface 420 that transects theanterior portion of the lens capsule 418. Likewise, the focal point ofthe electromagnetic radiation beam can be scanned to form a posteriorcapsulotomy closed incision boundary surface 430 that transects theposterior portion of the lens capsule 418.

The anterior and/or posterior closed incision boundary surfaces 420, 430can be designated using any suitable approach. For example, a plan viewof the patient's eye can be obtained using the camera 62. A capsulotomyincision designator 422 can be located and shown superimposed on theplan view of the patient's eye to illustrate the size, location, andshape of a planned capsulotomy relative to the patient's eye. Thecapsulotomy incision designator 422 can be manually defined by anoperator of the laser surgery system 10 and/or the laser surgery system10 can be configured to generate an initial capsulotomy incisiondesignator 422 for operator verification and/or modification.

The anterior capsulotomy closed incision boundary surface 420 can bedefined on a projection of the capsulotomy incision designator 422 suchthat the anterior capsulotomy closed incision boundary surface 420transects the anterior portion of the lens capsule 418 at all locationsaround the anterior capsulotomy incision boundary surface 420 for allexpected variations in the location of the anterior portion of the lenscapsule 418 relative to the projection of the capsulotomy incisiondesignator 422. For example, a curve corresponding to the capsulotomyincision designator 422 can be projected to define an intersection witha minimum depth mathematical surface model (e.g., a spherical surface)defining a minimum expected depth configuration for the anterior portionof the lens capsule 418 with the resulting intersection being ananterior capsulotomy upper closed curve 424 that defines an upperboundary for the anterior capsulotomy closed incision boundary surface420. Likewise, the curve corresponding to the capsulotomy incisiondesignator 422 can be projected to define an intersection with a maximumdepth mathematical surface model (e.g., a spherical surface) defining amaximum expected depth configuration for the anterior portion of thelens capsule 418 with the resulting intersection being an anteriorcapsulotomy lower closed curve 426 that defines a lower boundary for theanterior capsulotomy closed incision boundary surface 420.Alternatively, the focal point can be scanned using a low imaging-onlypower level (e.g., a power level sufficient to provide for imaging ofthe intraocular target via processing of the signal generated by thedetection sensor 54 of the confocal detection assembly 14 withoutmodifying the intraocular target) along the projection of thecapsulotomy incision designator 422 while varying the depth of the focalpoint to determine the depth of the anterior lens capsule at asufficient number of locations around the projection of the capsulotomyincision designator 422. The measured depths of the anterior lenscapsule can then be used to determine suitable anterior capsulotomyupper and lower boundary curves 424, 426 of the anterior capsulotomyclosed incision boundary surface 420.

Corneal Incisions

The laser surgery system 10 can be used to form any suitably shapedarcuate, primary, or sideport incisions.

FIGS. 9A through 9C illustrate aspects of arcuate incisions of a corneathat can be formed by the laser surgery system 10, according to manyembodiments. FIG. 9A shows an en face view of arcuate incisions withinthe optical zone of the cornea that can be formed using the lasersurgery system 10. The optical zone can be user-adjustable within, forexample, the range of 2 mm-11 mm. For asymmetric arcuate incisions, theoptical zone can be independently adjustable for each incision. Arclength can be user-adjustable within, for example, the range of10°-120°.

FIG. 9B shows a cross-sectional view of an arcuate incision in thecornea that can be formed using the laser surgery system 10 and thatpenetrates the cornea anterior surface and has an uncut posteriorportion. FIG. 9C shows a cross-sectional view of an arcuate intrastromalincision in the cornea that can be formed using the laser surgery system10. The arcuate intrastromal incision has an uncut anterior portion andan uncut posterior portion. Side cut angle can be user-adjustablewithin, for example, the range of 30°-150°. Uncut posterior and anteriorportions can be user-adjustable within, for example, the range of 100μm-250 μm or 20%-50% of the cornea thickness. Cornea thickness can bemeasured at the projected intersection of the incision with the corneaanterior/posterior measured at 90° to anterior/posterior cornea surfaceregardless of what side cut angle is chosen.

FIG. 10A shows an en face view of a primary cataract incision in thecornea that can be formed using the laser surgery system 10. The primarycataract incision provides access to surgical tools used to, forexample, remove a fragmented crystalline lens nucleus and insert in anIOL. FIG. 10B shows a cross-sectional view of a primary cataractincision of the cornea that can be formed using the laser surgery system10. Limbus offset can be user-adjustable within, for example, the rangeof 0.0 mm-5.0 mm. Width can be user-adjustable within, for example, therange 0.2 mm-6.5 mm. Length can be user-adjustable within, for example,the range of 0.5 mm 3.0 mm. Side Cut Angle can be user-adjustablewithin, for example, the range of 30°-150°. Plane depth can beuser-adjustable within, for example, the range of 125 μm-375 μm or25%-75% of the cornea thickness. Length can be defined as the en faceview distance between the projected incision intersection with thecornea anterior and the cornea posterior. FIG. 10C shows across-sectional view of a primary cataract incision that includes anuncut anterior portion. FIG. 10D shows a cross-sectional view of aprimary cataract incision that includes an uncut posterior portion. FIG.10E shows a cross-sectional view of a primary cataract incision thatincludes an uncut central length. And FIG. 10F shows a cross-sectionalview of a primary cataract incision that includes no uncut portion. SideCut Angle can be user-adjustable within, for example, the range of30°-150°. Uncut central length can be user-adjustable within, forexample, the range of 25 μm 1000 μm.

FIG. 11A shows an en face view of a sideport cataract incision in thecornea that can be formed using the laser surgery system 10. Thesideport cataract incision provides access for surgical tools used, forexample, to assist in the removal of a fragmented crystalline lens. FIG.11B shows a cross-sectional view of a sideport cataract incision of thecornea that has an uncut posterior portion and can be formed using thelaser surgery system 10. Limbus offset can be user-adjustable within,for example, the range of 0.0 mm-5.0 mm. Width can be user-adjustablewithin, for example, the range 0.2 mm-6.5 mm. Length can beuser-adjustable within, for example, the range of 0.5 mm 3.0 mm. FIG.11C shows a cross-sectional view of a sideport cataract incision thatincludes an uncut anterior portion. FIG. 11D shows a cross-sectionalview of a sideport cataract incision that includes an uncut centrallength. And FIG. 11E shows a cross-sectional view of a sideport cataractincision that includes no uncut portion. Side Cut Angle can beuser-adjustable within, for example, the range of 30°-150°. Uncutcentral length can be user-adjustable within, for example, the range of100 μm-250 μm or 20%-50% of the cornea thickness. Cornea thickness canbe measured at the projected intersection location of the incision withthe cornea anterior/posterior measured at 90° to the anterior/posteriorcornea surface regardless of what side cut angle is chosen.

Video and Confocal Imaging of Incision Locations

Although many different imaging techniques may be used in differentembodiments, a combination of video/camera imaging and confocal imagingbased on pulsed laser raster scanning of the tissue to be treated ispreferred.

As illustrated in the embodiment of FIG. 1, video imaging of the tissueto be treated, preferably a human eye, can be achieved by a camera 62and associated video illumination 64 integrated with the scanningassembly 18. The camera 62 and the beam 28 share a common optical paththrough the objective lens assembly 20 to the eye. A video dichroic 66is used to combine/separate the beam 28 with/from the illuminationwavelengths used by the camera. In one embodiment, the beam 28 can havea wavelength of between 320 and 370 nm, preferably about 355 nm, and thevideo illumination 64 can be configured to emit illumination havingwavelengths greater than 370 nm, or more than 400 or more than 450 nm.Accordingly, the video dichroic 66 can be configured to reflect the beambetween 320 and 370 nm wavelength while transmitting wavelengths greaterthan 370 nm, thus facilitating video imaging of the eye withoutinterference from beam 28. The resulting video image is preferably an enface image as shown in FIG. 13. The location of the capsulotomy incisionand any corneal incision specified by the physician can be projectedonto the video image prior to treatment as expected scan locations foreach respective incision.

In many embodiments, the imaging of the eye 24 further includesconfocally imaging one or more portions of the tissue, preferably theeye, to be treated. Any suitable device, assembly, and/or system, suchas described herein, can be used to confocally image one or moreportions of the eye or other tissue to be imaged. The confocal imagingmethods used herein generally include using a beam source, preferably apulsed laser source, to generate an electromagnetic radiation beam;propagating the electromagnetic radiation beam to a scanner along anoptical path to the eye; focusing the electromagnetic radiation beam toa focal point at a location within the eye; using the scanner to scan,preferably raster scan, the focal point to different locations withinthe eye; propagating a portion of the electromagnetic radiation beamreflected from the focal point location back along the shared opticalpath to a sensor; and generating an intensity signal indicative of theintensity of a portion of the electromagnetic radiation beam reflectedfrom the focal point location and propagated to the sensor. The methodcan include modifying polarization of at least one of theelectromagnetic radiation beam and a portion of the electromagneticradiation beam reflected from the focal point location. The method caninclude using the polarization-sensitive device to reflect a portion ofthe electromagnetic radiation beam reflected from the focal pointlocation so as to be incident upon the sensor.

Based on the calibration of the system described herein, the focal pointlocation of the confocally detected light can be related to the physicallocation of the focal point within the eye, and the location within theeye and the magnitude of the intensity at each location can be used toidentify boundaries, edges and layers within the eye. Boundaries, edgesand layers may be located in a confocal image by, for instance, Delaunaytriangulation and Dijkstra segmentation. These confocal images,including the boundaries, edges and layers can then be displayed to auser as a graphical representation of the areas of the eye to betreated.

In many embodiments, the lens capsule, and optionally a portion or allof the lens, are imaged using confocal imaging, and preferably, theseportions include the area of the lens capsule where the capsulotomy willbe placed. In general, the parameters necessary to define thecapsulotomy are input by a user or physician, and a raster scan with apulsed laser beam sweeps through the relevant portion of the lenscapsule for imaging the lens capsule. Based on the recorded location andmagnitude of the confocally reflected intensity measurements at eachlocation, the capsule is identified by image recognition, such as byDelaunay triangulation and Dijkstra segmentation, and the capsule shapeis fit to the segmented image. The resulting confocal image of lens maythen be shown to the physician for use in visualizing the capsulotomyincision.

In many embodiments, the methods and systems may include confocallyimaging a cornea by scanning one or more of portions of the cornea wherea primary incision, sideport incision or arcuate incision is to beplaced. In a preferred embodiment, one sectional image of the cornea isperformed for each selected corneal incision. These images arepreferably in the form of a section scan. As shown in FIG. 14, a sectionscan crosses cornea 500 along plane 510 and measures the confocalintensity at every location of a pulsed laser during the scan.Preferably, a section scan 510 comprises a raster scan of a pulsed laserbeam along the cornea 500, including the anterior surface 501 andposterior surface 502, on a vertical plane 510 centered at the corneaincision center and oriented along an incision's meridian. Thetrajectory goes from deep to shallow, inside the eye, crossing thecornea. The posterior and anterior boundaries of the cornea may beidentified in the image by, for instance, Dijkstra segmentation of theimage, and the resulting image may be provided to the user.

If the selected corneal incision is an arcuate incision, an“along-the-cut” imaging scan is also preferably performed. Analong-the-cut imaging scan may assist a physician in choosing thecorrect location for the arcuate incision in order to maintain anadequate depth and avoid posterior penetration. The “along the cut” scanpreferably has the same conical shape as the arcuate incision and isinclusive of the entire area to be covered arcuate incision. The conicalsector in the “along the cut” scan is mapped into a rectangular domain520 defined by the conical coordinates. The resulting conical image issegmented and fit. Optionally, the resulting fits to the anterior andposterior surfaces of the cornea are used to construct the arcuates,which can then are overlaid on their sections and “along the cut” scans.

In many embodiments, the optical surface of the eye is fit with one ormore with one or more of a Fourier transform, polynomials, a sphericalharmonics, Taylor polynomials, a wavelet transform, or Zernikepolynomials. The optical tissue surface may comprise one or more of theanterior surface of the cornea, the posterior surface of the cornea, theanterior surface of the lens capsule, the posterior surface of the lenscapsule, an anterior surface of the lens cortex, a posterior surface ofthe lens cortex, an anterior surface of the lens nucleus, a posteriorsurface of the lens nucleus, one or more anterior surfaces of the lenshaving a substantially constant index of refraction, one or moreposterior surfaces of the lens having a substantially constant index ofrefraction, the retinal surface, the foveal surface, a target tissuesurface to correct vision such as a target corneal surface, an anteriorsurface of an intraocular lens, or a posterior surface of an intraocularlens, for example.

Generating a Treatment Scan

After the relevant portions of the lens, lens capsule and cornea havebeen imaged, the incisions defined by the physician parameters may beprojected onto the image, and a treatment scan of the laser light beamis generated. The treatment scan preferably consists of a continuous setof x, y, z points arranged in space that are designed to carry out theincisions defined by the user. The location of the treatment scans areprojected onto at least one of the video and confocal images in order todefine the set of expected scan locations of the incisions.

Detecting an Actual Location of a Scan by Luminescence

Certain components of eye tissue absorb light having wavelengths of 370nm and less and emit red-shifted light (due for instance, to eitherfluorescence or phosphorescence) at wavelengths greater than 370 nm. Theemitted light from the eye tissue is also passed by dichroic 66 in FIG.12. Thus, when the focal point of beam 28 is scanned across the tissueto be treated, the location of the focal point of beam 28 within thetarget tissue can be tracked by camera 62 based on the knownrelationship between the pixels of the camera 62 and the location of thefocal point in the treatment space as established by the calibrationdescribed above.

FIG. 12 schematically illustrates using a luminescence from an eye 24 toobtain a video image of the actual location of a laser scan. Eye 24includes one or more components that emit light in response to absorbingelectromagnetic radiation at wavelengths preferably less than 370 nm.The eye 24 is preferably connected to the objective 20 and scanningassembly 18 via patient interface 22. Light from light source 12 isdirected to eye 24 via the confocal assembly 14, the shared optics 16the scanner 18 and the objective 20. With the focal point of theelectromagnetic radiation beam from light source 12 disposed, preferablysequentially, within the eye, the camera 62 is used to detect the actuallocation of the resulting emission from eye 24 based on the position ofthe focal point within eye 24. The luminescence is generally detected asone or more pixels, Pact. The observed location of the resultingfluorescent emission can be used in conjunction with calibration datafor the camera 62 to determine x and y coordinates of the associatedfocal point in the treatment space and can be compared to the expectedscan location of the incisions.

The camera image of the eye is preferably presented to a user as an enface image, such as shown in FIG. 13 with the pixels, Pact,corresponding to the actual location of the scan illuminated on theimage.

The above described methods and systems permit a physician to verify theactual scan location of a contemplated incision in comparison to itsexpected location and also to confirm that the laser surgical system isadequately calibrated. For example, if the physician desired to make acut at a predetermined position in an eye, the physical need only enterthe necessary parameters to define the location and type of incision thephysician intends to make. In one embodiment, the laser surgical systemof the present invention is configured to receive these parameters andto project the defined incision onto a video image. In some embodiments,the video image then illustrates the expected position of the incisionon the image, by, for instance, illuminating a set of Pixels, PEL,corresponding to the intended location of the incision. The laser systemis also preferably configured to carry out a treatment scan configuredto make the incision at the predetermined location. As the pulsed laserscans the tissue, a resulting luminescence from the location of thetreatment scan is detected and subsequently used to identify the actuallocation in the eye where the treatment scan was performed. Preferably,the actual location is illustrated on the video image by illuminating aset of pixels, Pact, corresponding to the position of the actual scan.Thus, in some embodiments, if the actual location of the scan differsfrom the expected location, the physician can visually make thisdetermination by inspection of the video image.

In another embodiment, a warning is issued if a difference between theactual location and the expected location is greater than apredetermined threshold amount. This makes it possible to warn aphysician or user, or stop the scan completely, even if the physician isnot actively viewing the image.

Preferably, the system and methods are used throughout the entirety ofthe treatment scan. Specifically, in some embodiments, the progressionof the treatment scan is monitored by successive images/frames capturedduring the treatment. In a preferred embodiment, successive frames ofthe image capture the progression of the treatment scan in real time. Insome embodiments, the difference in detected luminescence between framestrack actual location and actual direction of the treatment scan. Forexample, when a confocal scan is being taken, a video is taken at thesame time. In this manner, the system and methods can ensure that theentirety of the incision is placed at its expected location.

The methods described herein also provide a convenient method forconfirming that a laser eye surgery system is adequately calibrated.With conventional imaging, a number of safeguards are generally in placeto ensure proper calibration; however, a physician may have limitedconvenient procedures for determining whether the instrument iscalibrated. The present invention allows the physician or other user toquickly assess the calibration of the laser surgical system.

It is also noted that the present invention provides a safeguard shouldthe physician inadvertently type in the wrong coordinates for his cuts.In that scenario, the calibration would not necessarily be wrong but thephysician would notice that the cutting was not taking place in thecorrect locations. This event would presumably prompt the physician todouble check to see if he typed in the correct geometric coordinates.Further, this method would provide a safeguard should the calibration beoff before a procedure by the inadvertent bumping of the camera orthings of that nature.

In sum, many embodiments provide a method or system that detects anactual location of a laser scan within an object and verifies whetherthe laser scan is at the expected location. Other embodiments provide amethod or system that detects an actual placement of an ocular incisionwithin an eye and verifies whether the ocular incision is at theintended location. Other embodiments provide a method of verifying thecalibration of a laser eye surgical system.

It is to be understood that the present invention is not limited to theembodiment(s) described above and illustrated herein, but encompassesany and all variations explicitly and implicitly derived therefrom.Although not shown in the figures, multiple imaging steps can also beemployed in between treatment steps to account for any changes inposition and/or size due to treatment and further insure the accuratedisposition of laser energy in the target tissue.

All patents and patent applications cited herein are hereby incorporatedby reference in their entirety.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

While certain illustrated embodiments of this disclosure have been shownand described in an exemplary form with a certain degree ofparticularity, those skilled in the art will understand that theembodiments are provided by way of example only, and that variousvariations can be made without departing from the spirit or scope of theinvention. Thus, it is intended that this disclosure cover allmodifications, alternative constructions, changes, substitutions,variations, as well as the combinations and arrangements of parts,structures, and steps that come within the spirit and scope of theinvention as generally expressed by the following claims and theirequivalents.

The invention claimed is:
 1. A method of verifying the calibration of alaser eye surgical system, comprising: imaging at least a portion of acalibration apparatus, the calibration apparatus including a containerhaving a viscous substance or a solid substance, and either an irisstructure or a lens structure having a luminescence emissive surface,the resulting image comprising a predetermined location for a laserscan; identifying the predetermined location in the image, therebyestablishing an expected scan location of the laser scan in the image;performing the laser scan of the calibration apparatus by scanning afocal point of the laser beam in a scanned area, the laser beam having awavelength; detecting a luminescence from the scanned area withoutreceiving or detecting a reflected light from the eye tissue having asame wavelength as the wavelength of the laser beam, and identifying anactual scanned location within the image based on the detectedluminescence; and determining whether the laser surgical system iscalibrated based on a difference between the actual scanned location andexpected scan location.
 2. The method of claim 1, wherein the laser beamis a pulsed laser beam having a wavelength of 320 nm to 370 nm.
 3. Themethod of claim 1, wherein the luminescence has a wavelength of 400 nmor more.
 4. The method of claim 1, wherein the image comprises an arrayof pixels.
 5. The method of claim 4, wherein the expected scan locationcomprises one or more pixels selected from amongst the array of pixels.6. The method of claim 4, wherein the actual location comprises one ormore pixels selected from the array of pixels.
 7. The method of claim 4,wherein the method further comprises: periodically re-imaging thecalibration apparatus, thereby obtaining one or more successive images,identifying an actual scanned location by comparing a detectedluminescence of a same pixel in the array between two of the successiveimages.
 8. The method of claim 7, wherein the method further comprises:identifying a direction of the scan by comparing an actual scannedlocation in between two or more of the successive images.
 9. The methodof claim 1, where verifying the laser scan at the predetermined locationcomprises determining whether a distance between the actual scannedlocation and the expected scan location is within a predeterminedthreshold.